PM Conversion Research Articles

Reducing the impact of biomass combustion in residential units on local air quality by using innovative low-loading Pt-based heterogeneous catalyst

There are several published studies evaluating the potential of platinum and palladium-based catalysts for real flue gas purification, however, the need to reduce the mass fraction of precious metals and the effect of this process is often neglected. This study aimed to assess the influence of two catalysts on the overall flue gas composition formed during combustion in a pellet burner operated to mimic the operation of a real wood log stove. Commercial Pt–Pd-based (CAT A) and Pt-based (CAT B) catalysts with innovative sol-gel coatings and a reduced amount of active substance were used. The CO, OGC and PM conversion rates of CAT A reached 87.8%, 37.0% and 25.2%, while the removal efficiency of CAT B reached 85.8%, 37.8% and 18.8%, respectively. The decrease of organic carbon by the catalysts ranged from 28% to 49% in the case of CAT A and from 13% to 60% in the case of Cat B. The concentrations of PAHs emitted seem to indicate a less carcinogenic composition when catalytic converters are used than without these flue gas treatment units.

Results of application of porous permeable SHS catalytic blocks in multistage converters, 
 diesel exhaust gases

BACKGROUND: According to the statements of leading experts in the diesel industry, in order to introduce standards for the levels of harmful emissions into the atmosphere, it is necessary to use particulate filters and catalytic converters, which will increase the efficiency of exhaust gas conversion and improve the environmental performance of diesel engines.
 AIMS: Educing harmful emissions into the atmosphere, improving the quality and reducing the cost of cleaning exhaust gases during the implementation of the life cycles of transport energy facilities by using porous SHS blocks in catalytic converters and particulate filters.
 METHODS: Stand tests of prototypes of neutralizers of the AltSTU design with one, two and three stages of purification were carried out. The first stage is a particulate filter made of porous permeable SHS material, the second stage is an oxidizing SHS block, the third stage is a catalytic reducing SHS block. To obtain catalytic blocks by the SHS method, the following charge composition was used: iron scale 18X2H4MA -47.5%; chromium oxide PH-1 according to TU 882-76 17.7%; nickel powder PNK-OT-1 according to GOST 9722-79 4.9%; aluminum powder according to TU 485-22-87 grade ASD-1 15%, copper 11%; aluminum oxide 3.8%; iridium 0.01%. The charge of the recovery unit consisted of 14.5% copper. The resulting blocks had a permeable structure and high strength. The average pore size was 180 microns. Neutralizers were installed butt-to-butt with a turbocharger.
 RESULTS: It was revealed that NOx emissions according to the load characteristic of the KamAZ-740 diesel engine at 2600 min-1 decrease at average effective pressures Pe equal to 0.03; 0.55; 0.77 MPa from 3.82...11.62...9.49 g/m3, respectively, to 3.23...6.52...4.61 g/m3 or approximately 13...44...53%. Reduction of emissions of solid particles at the same loads was 75; 45; 63%, of hydrocarbons 72; 53; 54%. The minimum specific fuel consumption was observed in the range of 1600...2000 min-1 according to the external speed characteristic. When using a neutralizer with two catalytic units installed in series, emissions from hydrocarbon exhaust decreased from 3.12...1.21 to 0.90...0.29 g/m3, or by 71...76%. The degree of CO conversion was 78...73%; NOx 4...52%, and the total purification coefficient was a coaxial installation of additional blocks made of SHS-catalytic materials has led to an improvement in the quality of cleaning up to =0,698. Over 360 hours of operation, the efficiency of PM conversion decreased from 55 to 45%, CO from 58 to 46%, NOx from 65 to 44%, which indicated the beginning of deactivation of catalysts.
 CONCLUSIONS: The use of multi-stage neutralizers with SHS-catalytic units can reduce emissions of hydrocarbons by 1.95 times, carbon monoxide by 3.6 times, nitrogen oxides by 2 times, solid particles by 3 times, ensuring compliance with Russian standards.

Power spectral density analysis of relative comb-line phase jitter in a twin-soliton molecule

Investigation on the relative phase evolution between two bounded optical solitons is essential for its potential applications in development of larger telecommunication capacity of optical fiber transmission lines, resolution improvement in advancing ultrafast characterization approaches and development of all-optical information storage. Here we characterized relative comb-line phase jitter power spectral density (PSD) of a soliton molecule pair generated from a passively mode-locked Er:fiber laser. Through tracking the intensity difference between two selected wavelengths in one certain spectral interference fringe, the relative comb-line phase noise PSD is measured by balanced detection. The estimated measurement resolution is at 10−14 rad2/Hz level and the estimated integrated phase noise from 10 MHz to 100 Hz is 2.04 mrad. The estimated relative linewidth is far below 1 mHz. Comparison between phase noise PSD and intensity noise PSD indicates that AM–PM conversion plays an important role in relative phase jitter dynamics between the two solitons. Our spectral interference fringe tracking technique is attractive for its simplicity and shows potential in ultra-high resolution in phase noise measurement, providing an ultra-sensitive alternative approach for relative phase noise stabilization of optical soliton molecules, two independent mode-locked lasers and optical length stabilization of interferometers.

Satellite AOD conversion into ground PM10, PM2.5 and PM1 over the Po valley (Milan, Italy) exploiting information on aerosol vertical profiles, chemistry, hygroscopicity and meteorology

Satellite data are fundamental for air quality monitoring. Despite this, several algorithms are present in literature leaving to the reader a choice on the best approach without considering the physical – spatial – temporal inconsistencies concerning the problem of relating satellite with ground-based data. In order to overcome this dilemma, the present work was carried out developing a general methodological approach to overcome the aforementioned inconsistencies obtaining in any region the best retrieval. In this respect, the particulate matter phenomenology (both at ground and vertically) was considered in order to select the best approach for the AOD to PM conversion starting from the knowledge of PM properties, meteorology and vertical behaviour.In this respect, multiple years of particulate matter vertical profiles, chemical composition, hygroscopicity, meteorology and optical properties were used to define an optimized satellite AOD-ground PM relationship. A hybrid algorithm (physically based and statistical) was developed to be applied over the Milan conurbation (Po Valley) to determine ground-level PM1, PM2.5 and PM10 concentrations from satellite aerosol optical depth (AOD) data. The developed algorithm (based on aerosol optical depth, mixing height, wind speed and PM concentrations of the previous day) showed high accuracy enabling to predict ground particulate matter concentrations with very low RMSE in prediction (5.48 μg/m3, 9.89 μg/m3 and 10.64 μg/m3 for PM1, PM2.5 and PM10) and rather high R2 (≥0.83 on the evaluation set of data).

A new modified I-MOS varactor for linear range enhancement

High linear MOS varactors can reduce AM to PM conversion and phase noise of the LC-VCOs. In this paper, a new technique is presented to increase the linear range of MOS varactors by reducing the slope of the C–V characteristic in linear region. In the proposed method, instead of using only one MOS varactor with aspect ratio of W/L, several varactors (e.g. n = 2, 3, …) with (W/n)/L are connected in parallel. The substrate of each varactor is biased at different voltage to shift its C–V linear region by changing the threshold voltage. In this way, each sub-varactor in the proposed structure covers different linear region of the whole varactor. Hence, the overall linear range of the parallel varactors can be significantly increased by correctly biasing of the substrates. To verify the proposed method, a MOS varactor including 6 parallel sub-varactors is designed in a commercial TSMC 0.18 μm CMOS Technology. Simulation results show 4× improvement of the linear range than conventional varactors and nearly constant VCO gain in tuning range. Furthermore, using the proposed varactor in a conventional LC oscillator, 10 dB improvement of the phase noise is achieved.

Design and implementation of a high efficiency RF power amplifier for S-band telemetry subsystems

In this paper we present design, implementation and characterization of a high efficiency radio frequency (RF) power amplifier (PA) for S-band telemetry subsystems. The proposed RF PA has been implemented using an AlGaN/GaN Hot Electron Mobility Transistor (HEMT) die and shows 50W output power with a highly linear power gain in required bandwidth. Central frequency of the proposed telemetry can be tuned from 2200 to 2290MHZ. It works in E class with 28V power supply voltage and achieves more than 63% efficiency in working bandwidth. Considering the tradeoff between power efficiency and linearity, to achieve the required linearity of π/4-DQPSK modulation, we have tried to implement our structure near to EB-class instead of E-class. Two tone Intermodulation Distortion Third Harmonic (IMD3) in this condition is better than −26dBc in-band. Also, AM to AM conversion is better than 0.3dB/dB and AM to PM conversion is less than 3.5Deg/dB. For the proposed PA design a Rogers printed circuit board (PCB) on a Cu hot plate for better thermal transferring has been used. All of the pads are bonded to PCB with 25μm gold bonding wires directly.

A Comprehensive Analysis of AM–AM and AM–PM Conversion in an LDMOS RF Power Amplifier

In this paper, a Volterra analysis built on top of a normal harmonic balance simulation is used for a comprehensive analysis of the causes of AM-PM distortion in a LDMOS RF power amplifier (PA). The analysis shows that any nonlinear capacitors cause AM-PM. In addition, varying terminal impedances may pull the matching impedances and cause phase shift. The AM-PM is also affected by the distortion that is mixed down from the second harmonic. As a sample circuit, an internally matched 30-W LDMOS RF PA is used and the results are compared to measured AM-AM, AM-PM and large-signal S11.

Investigation of the non-linear input capacitance in LDMOS transistors and its contribution to IMD and phase distortion

In this paper the mechanisms causing the capacitive, reactive non-linearities in a lateral double diffused MOS, LDMOS, transistor are investigated. The non-linear input capacitance under load-line power match is extracted and analyzed. Computational TCAD load-pull is used to analyze the effect of non-linear capacitance on two-tone intermodulation distortion and AM–PM conversion in class-A operation. High-frequency measurements have been made to verify the use of 2D numerical device simulations for the analysis. It is found that the input capacitance, Cgg, of the LDMOS transistor working under power match conditions is a strongly non-linear function of gate voltage Vg but with an almost linear initial increase in Cgg. The voltage dependence of Cgg is found to mainly affect higher order IMD products in class-A operation. Transient simulations however show that Cgg seriously contributes to the onset of AM–PM conversion well below the 1dB compression point.

Effects of low noise amplifier non‐linearities on blind adaptive beamforming performance in CDMA wireless systems

AbstractWe report a new approach to analyse the effects of low noise amplifier (LNA) non‐linear distortions in the code division multiple access (CDMA) wireless communication systems using spatio‐temporal analysis and Volterra series theory. For this purpose, the bit error rate (BER) performance of three blind algorithms is studied based on post correlated model of received signal, and a time‐varying multiple vector channel model which is an extended form of the Gaussian wide sense stationary uncorrelated scattering (GWSSUS) channel. By using the Volterra series theory, an analytical expression for amplitude modulation to phase modulation (AM–PM) conversion is determined as a phase statement of LNA compression. In this approach, by combining the analytical expression for AM–PM conversion and CDMA blind beamforming techniques, we evaluate the AM–PM distortion effects on BER performance of a CDMA system originated from multiple non‐linear LNA blocks. Simulation results show that conditions are found to minimize AM–PM conversion introduced by multiple non‐linear blocks in the system leading to low BER. Copyright © 2006 John Wiley & Sons, Ltd.

AM–PM conversion introduced by MESFET and HBT

AbstractThe AM–PM conversion introduced by microwave transistors was researched using the approach of the AM–PM conversion as a phase statement of compression and desensitization. As proven in this article, the presented approach permits developing high linear amplifiers optimizing their AM–PM conversion instead of optimizing the intermodulation distortion, as it is usually accomplished. The effect of frequencies and amplitudes of input signals, load resistance, and bias condition on the AM–PM conversion introduced by MESFET and HBT amplifiers are reported. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 319–321, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10307

AM-PM conversion introduced by weakly nonlinear circuits

This paper is related to a novel model for the AM–PM conversion characterization of systems. By means of nonlinear transfer function analysis, AM–PM conversion is obtained as a phase statement of compression and desensitization, thus immunity against electromagnetic interference of radio systems can be evaluated when the signal undergoes fading or when it is received with interfering oscillations. The model is used to obtain the AM–PM conversion introduced by a feedforward amplifier. The results show that the maximum compensation of third-order intermodulation does not necessary coincide with the minimum AM–PM conversion condition.

Spice model for AM–PM conversion introduced by weakly nonlinear circuits

An algorithm is installed into the Spice code for simulating AM–PM conversion as a phase statement of compression and desensitisation phenomena. The algorithm is based on a novel model suitable for analysis of the AM–PM conversion introduced by weakly nonlinear circuits. The Berkeley Spice version 3F5 source code was modified to obtain the compression and desensitisation coefficients and the AM–PM conversion in weakly nonlinear circuits as a phase statement of compression and desensitisation effects. Results of the simulation of the AM–PM conversion introduced by a microwave GaAs FET amplifier are reported.

44% efficiency operation of power heterojunction FET at near pinch-off for 3.5 V wide-band CDMA cellular phones

This paper describes 1.95 GHz power performance of a double-doped AlGaAs/InGaAs/AlGaAs heterojunction FET (HJFET) operated at 3.5 V drain bias voltage for Wide-band CDMA (W-CDMA) cellular phone systems. An HJFET with a novel multilayer cap and a narrow recess structure showed a low on-resistance ( R on) of 1.4 ohm mm. With an optimum output impedance matching at a reduced quiescent drain current of 80 mA (less than 1% of the maximum drain current), the HJFET exhibited a high power added efficiency (PAE) of 44.2% with an output power of 600 mW (28.0 dBm) and an adjacent channel leakage power ratio (ACPR) of −43 dBc at 5 MHz off-center frequency. This high PAE obtained was ascribed to an ACPR dip behavior with respect to the input power at around the W-CDMA criteria. Through an ACPR simulation with measured AM–AM and AM–PM conversion characteristics, the AM–AM conversion characteristic was found to dominate the W-CDMA ACPR rather than the AM–PM conversion.

A 60-dB gain, 55-dB dynamic range, 10-Gb/s broad-band SiGe HBT limiting amplifier

A limiting amplifier IC implemented in a silicon-germanium (SiGe) heterojunction bipolar transistor technology for low-cost 10-Gb/s applications is described. The IC employs 20 dB gain limiting cells, input overload protection, split analog-digital grounds, and on-chip isolation interface with transmission lines. A gain enhancement technique has been developed for a parallel-feedback limiting cell. The limiting amplifier sensitivity is less than 3.5 mV/sub pp/ at BER=10/sup -9/ with 2-V/sub pp/ maximum input (55-dB dynamic range). The total gain is over 60 dB, and S/sub 21/ bandwidth exceeds 15 GHz at 10-mV/sub pp/ input. Parameters S/sub 11/ and S/sub 22/ are better than -10 dB in the 10-GHz frequency range. The AM to PM conversion is less than 5 ps across input dynamic range. The output differential voltage can be set from 0.2 to 2 V/sub pp/ with IC power dissipation from 250 mW to 1.1 W. The chip area is 1.2/spl times/2.6 mm/sup 2/. A 10-Gb/s optical receiver, built with the packaged limiting amplifier, demonstrated -19.6-dBm sensitivity. The IC can be used in 10-Gb/s fiber-optic receivers requiring high sensitivity and wide input dynamic range.

Performance study of 16‐ary deqam modem for future satellite communication systems

AbstractThis paper investigates the effects of additive white Gaussian noise (AWGN), adjacent‐channel interference (ACI) and co‐channel interference (CCI) combined with flat fading on the performance of bandlimited 16‐ary differentially encoded quadrature amplitude modulation (16‐ary DEQAM) signalling transmitted through a non‐linear high‐power amplifier (HPA). It is assumed that the HPA exhibits both AM‐AM and AM–PM conversion distortions. This situation may be applied to the up‐link or down‐link of a regenerative satellite system where the HPA is the earth‐station travelling‐wave tube (TWT) or the on‐board TWTA, respectively. The signal‐to‐noise ratio (SNR) degradations at a specific bit error rate (BER) are evaluated by means of a series of computer simulation tests for various values of channel roll‐off factor α (channel bandwidth) and different degrees of output backoff (OBO) of the HPA in the presence of various combinations of the channel impairments. It is shown that by employing a baseband or RF predistortion technique for the HPA and selecting the best arrangement of channel roll‐off factor, OBO value of the HPA and channel spacing, a good performance can be achieved regarding the most efficient use of bandwidth together with a minimum SNR degradation due to the presence of channel impairments. Thus, the use of 16‐ary DEQAM for satellite communications is feasible in the near future.

Effects of baseband predistortion at the transmitter on the performance of a DEQPSK satellite modem

AbstractThe paper presents the results of an extensive series of computer‐simulation tests to determine the effects of bandlimiting, nonlinear distortion with and without predistortion, and adjacent channel interference (ACI), on the tolerance to additive white Gaussian noise of a digital satellite modem. The modem transmits a differentially encoded quaternary phase‐shift keyed (DEQPSK) signal over a satellite link, where the high‐power amplifier (HPA) at the earth‐station transmitter may introduce AM—AM and AM—PM conversion effects into the DEQPSK signal, but the satellite transponder is linear. Four different bandwidths of the transmitted signal are tested, together with three different levels of output back‐off in the HPA at the transmitter. The predistorter operates on the baseband signal at the input to the modulator in the transmitter and assumes a prior knowledge of the HPA characteristics. ACI can be introduced into the transmitted DEQPSK signal by the corresponding DEQPSK signals, which occupy the two immediately adjacent frequency bands. The latter signals are assumed to have the same transmission rate and bandwidths as the first signal.Various combinations of the different distortion and interference effects are studied, using an equivalent baseband model of the transmission system, and the arrangements selected are those achieving the most efficient use of bandwidth together with the best tolerance to additive white Gaussian noise. A surprisingly good performance is achieved.

High-performance amplitude and phase digitizers at 60 MHz

We describe high-performance successive approximation amplitude and phase digitizers capable of resolving 1 part in 4096 in amplitude and 0.1° in phase at a rate of 50 000 points per second. They communicate with a computer workstation by DMA over a GPIO bus. The phase digitizer exhibits negligible AM to PM conversion and an input amplitude range of 70 dB. Both digitizers reside on one thick 7×9-in. card module. The system is currently used in an electronically scanned laser microscope. We also describe a high-precision phase calibrator and associated calibration software.

Intercarrier Buss Phenomena Analysis and Cures

This partly tutorial paper defines buzz as the result of video related incidental phase modulation (IPM) of the intercarrier. The main sources of IPM are 1. parametric and transit time effects, both non-linear in character and 2. AM to PM conversion of a strictly linear character. 1. is the main source of transmitter visual IPM but can also take place in the receiver. Linear AM to PM is prominent in the receiver as Nyquist IPM.

Energy transfer in the purple membrane of Halobacterium halobium

The absorption spectrum of the primary photoproduct (the bathoproduct, or K) of the purple membrane protein (PM) at-196 degrees C has a maximum at 628 nm and an extinction coefficient of 87,000. Knowing the absorption spectrum allowed us to calculate the quantum efficiencies for PM to K and K to PM conversion at -196 degrees C. Direct measurements of these quantum yeilds at -196 degrees C gave 0.33 +/- 0.05 and 0.67 +/- 0.04, respectively. Determination of relative quantum efficiencies for PM to K and K to PM conversion by analysis of the absorption spectra of several photostationary-state mixtures of PM and K at -196 degrees C, however, gave wavelength-dependent quantum efficiencies that appear to be greater than 1. These anomolous results can be readily explained in terms of energy transfer from PM to K within the trimer clusters of pigment molecules which exist in the purple membrane. A model for such a transfer predicts an efficiency of energy transfer from PM to K of about 43%.

Multistage Gunn amplifiers for FM-CW systems

Waveguide cavity Gunn reflection amplifiers are discussed. Stabilization techniques are outlined, together with some typical pitfalls. Some conclusions are drawn as to how Gunn devices operate in amplifier service. Two special cases are discussed: a two-stage /SUP 1///SUB 2/-W Ku-band amplifier, a four-stage 30-dB gain X-band amplifier. Data are presented on bandwidth, noise, power variation with temperature, FM to AM conversion, intermodulation, AM to PM conversion and group delay distortion. In addition some data related to specific systems applications are presented.